ES2562229T3 - Support for at least one hot section bearing of turbomotor and associated turbomotor - Google Patents

Abstract

Support (14) for at least one bearing (13) of hot turbomotor section, which includes a central bushing (15) incorporating an outer bearing seat for receiving said bearing (13), an annular crankcase segment (16) around of the central hub (15) and a plurality of radial arms (17) joining said central hub (15) to said annular crankcase segment (16) and inclined in axial direction and in tangential direction characterized by said radial arms (17) they are integrated with the central hub (15) and the annular crankcase segment (16) in a single unit piece.

Description

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DESCRIPTION

Support for at least one turbomotor and associated turbomotor hot section bearing Background of the invention

The present invention relates to the domain of the turbomotors and, in particular, a support for at least one bearing of hot turbomotor section, this support including a central hub incorporating an outer bearing seat for receiving the bearing, an annular segment of crankcase around the central bushing and a plurality of radial arms connecting said central bushing to said annular crankcase segment.

By "turbomachine", in the present context, is meant any machine that allows the conversion of the thermal energy of a working fluid into mechanical energy by expanding said working fluid into a turbine. In the description that follows, the terms "upstream" and "downstream" are defined with respect to the normal flow direction of the working fluid in the turbomachine.

Typically, in such a turbomachinery, the working fluid is contained in an annular vein between a crankcase and at least one rotating shaft around a central axis. Said rotating shaft is integral in rotation with at least one turbomachine rotor crossed by said annular fluid vein. In order to support the rotor, the rotating shaft is supported by at least one bearing, which is in turn supported by a bearing support with a plurality of arms radially traversing the fluid vein to attach the bearing to the crankcase of the turbomachine

Among the different types of turbomachinery, turbomotors are specifically counted. In such a turbomotor, at least one turbine rotor located downstream of a compressor and a combustion chamber is coupled to an output shaft to recover the mechanical energy produced by the turbomotor. This distinguishes turbomotors specifically from turbojet engines, in which the recovery of mechanical energy is mainly effected by the expansion of combustion gases in a reaction nozzle. Consequently, in the hot section of a turbomotor, that is, in the combustion chamber and downstream of it, the thermal stresses are high due to the strong temperature gradients with respect to the size of the turbomotors. Especially the bearings and bearing supports located in the hot section are subject to particularly high thermomechanical stresses.

In order to respond to requests for tree line dynamics and control the turbine excentration under maneuvering, it is desirable to obtain high radial stiffness of the bearing supports, even at high temperatures. However, high rigidity of the bearing support can have a negative impact on its useful life.

In British patent GB 1,010,401, a turbomachine hot section bearing support has been proposed, in which a central hub is suspended from an annular segment of the turbomachine crankcase by inclined rods in radial and tangential direction. However, in order to accommodate the thermomechanical stresses between the hub and the annular crankcase segment, the ends of these rods are articulated. In addition, the rods are protected by tubular fairings whose outer ends can move slightly longitudinally with respect to the annular crankcase segment in order to accommodate these same thermomechanical stresses. Consequently, this bearing support has a very large complexity, from which high production and maintenance costs are derived.

Object and summary of the invention

The invention aims to propose a support for at least one hot section bearing of turbomotor that allows to obtain a high radial and flexural rigidity, even at high temperatures, with, however, a good service life and a great simplicity.

To do this, in at least one embodiment of the invention, said radial arms are inclined in axial direction and in a tangential direction and integrated with the central hub and the annular crankcase segment in a single unit piece. An axial direction inclination is understood in this context as an inclination with respect to the radial direction in a longitudinal plane aligned with the central axis of the bearing. Tilt in the tangential direction is understood, in this context, they join inclination with respect to the radial direction in a transverse plane perpendicular to the central axis of the bearing.

Thanks to the tangential inclination of the arms and their integration into a single unit piece with the central hub and the annular crankcase segment, these arms transmit a part of the radial loads of the bearing in flexion, rather than only in traction-, compression as the support rods according to British patent document GB 1,010,401, thus avoiding especially a radial punching of the annular crankcase segment at the roots of the radial arms thereon. On the other hand, the axial inclination reinforces the arms in flexion with respect to the radial loads, still allowing a sensible gain of the radial stiffness of the support. A highly rigid bearing support can thus be obtained with, however, a good service life even in such a demanding thermomechanical environment as that of the hot section of a turbomotor.

In particular, the support may also include at least one fixing flange on an axial end of said

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annular crankcase segment, and each radial arm be inclined axially, from a root on said annular crankcase segment, in the direction of the axial end that the fixing flange has. Thus it is possible to obtain a larger axial separation of the radial arms, with respect to said fixing flange, at the level of its roots on the annular crankcase segment than at the level of its roots on the central bushing. This axial separation over the ring segment of the crankcase makes it possible to better distribute the mechanical loads and thermal gradients between the radial arms and the fixing flange, and thus increase the life of the support, without damaging its overall stiffness. In order to better distribute the forces in the vicinity of the root of each arm over the annular crankcase segment, said fixing flange may be cut in front of the root of each radial arm over said annular crankcase segment. This avoids too great rigidity of the annular crankcase segment in the vicinity of this root that could generate concentrations of stresses that are too important. In addition, said fixing flange may have at least one positive engagement element, such as a pinion or a hole intended to receive a complementary pinion, for the absorption of stresses in a plane perpendicular to a central axis of the bearing.

In particular, in order to avoid excessively increasing the front surface, mass or radial flexibility of the support, and in order to avoid loading the radial arms only in flexion, said radial arms may have a tangential inclination angle p not exceeding 70 °.

In particular, in order to avoid excessively increasing the axial dimension of the support, and thus avoiding loading the radial arms too strongly in flexion, said radial arms may have an axial inclination angle of not more than 45 °.

In particular, in order to reduce the resistance of the support to the flow in the fluid vein, said arms can each have an aerodynamic profile with an angular deviation from an axial direction. The angular deviation orients the profile in the direction of a helical flow of the fluid vein in order to reduce its resistance to flow, and thus increases the flexural stiffness of the profile in the transverse plane. More particularly, said aerodynamic profiles may have a deflection angle and not greater than 30 °.

The invention also relates to a turbomotor that includes at least one bearing support of this type. In particular, said bearing support can be located adjacent downstream of a turbine rotor of the turbomotor and said radial arms are inclined axially upstream from said crankcase segment, which allows to limit the overhang between the arms of the support and the turbine rotor, while obtaining a certain axial separation between the blade heads of the turbine rotor and the root of the radial arms on the annular crankcase segment that allows to limit the vibratory aerodynamic loads. More particularly, in order to fix the bearing support to a turbine housing, said bearing support may include a fixing flange located on an axial end upstream of said annular crankcase segment. In this case, the axial inclination of the radial arms also makes it possible to obtain an axial separation between this fixing flange and the roots of the radial arms on the annular crankcase segment, in order to better distribute the thermal and mechanical stresses between the flange and the estate.

However, the bearing support can also be located alternately adjacent upstream of a turbine rotor of the turbomotor, for example.

In addition, this turbomotor can, in particular, include at least one compressor, a combustion chamber, a first combustion gas turbine coupled in rotation at least one compressor by a first rotating shaft, and a second combustion gas turbine coupled in rotation at a power outlet by a second rotating shaft, and said bearing support being a bearing support of the second rotating shaft, which allows to respond to the particularly high mechanical and thermal stresses to which a bearing support is typically subjected of free turbine in a turbomotor of this type. However, as an alternative or as a complement to this, at least one bearing support of the first rotating shaft can also be configured in the same way, with the arms inclined axially and tangentially, and possibly presenting an aerodynamic profile angularly offset with respect to to an axial direction.

Brief description of the drawings

The invention will be well understood and its advantages will appear better by reading the detailed description that follows, in an embodiment represented by way of non-limiting example. The description refers to the accompanying drawings in which:

- Figure 1 is a schematic longitudinal section of a turbomotor;

- Figure 2 s a schematic longitudinal section of a bearing support according to an embodiment of the

Invention;

- Figure 2A is a cross section of an arm of the bearing support of Figure 2 along a line IIA-IIA;

- Figure 3 is a front view of the bearing support of Figure 2;

- Figure 4 is a perspective view from the front of the bearing support of Figure 2; Y

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- Figure 5 is a detail view of the bearing support of Figure 2.

Detailed description of the invention

A turbomotor 1 is illustrated in Figure 1. This turbomotor 1 includes a gas generator segment 2 and a free turbine segment 3. The gas generator segment 2 includes an axial compressor 4, a radial compressor 5, a combustion chamber 6, a first combustion gas turbine 7 and a first rotary shaft 8, with a central axis X, and which rotates in rotation the wheels of the first combustion gas turbine 7 and the compressors 4, 5 such that the rotation of the latter serves to drive the compressors 4, 5 during operation of the turbomotor 1. The free turbine segment 3, located downstream of the gas generator segment 2, comprises a second combustion gas turbine 9, or "free turbine", and a second rotating shaft 10, also aligned with the central axis X and which couples the free turbine 9 with a power output 11. Thus, the rotation of the free turbine rotor 9 during operation of the turbomotor 1 can serve to drive a device external ossifier such as, for example, a helicopter rotor.

The rotating shafts 8, 10 are supported by bearings, which are supported by bearing supports that include pluralities of radial arms that pass through the gas vein 12. In particular, in the free turbine segment 3 of the illustrated embodiment, the second Rotary shaft 10 is supported by at least one bearing 13, which is in turn supported by a bearing support 14, located adjacent downstream of the rotor 22 of the free turbine 9, and which includes, in a single unit piece, a central bushing 15, an annular crankcase segment 16 and a plurality of radial arms 17, five for example, that pass through the gas vein 12 to connect the central bushing 15 to the annular crankcase segment 16. The bearing 13 is directly received in an outer bearing seat formed in the central hub 15, and the annular crankcase segment 16 has, on its upstream axial end, a fixing flange 18 for fixing the bearing support 14 to a housing turbine r 19. This fixing flange 18 has not only holes 30 intended to receive fixing bolts of the support 14, but also projecting pinions 31, intended to be received in complementary holes on a surface opposite to this flange 18 in order to obtain a positive fit that allows precise positioning of the support 14, as well as the absorption of stresses in a transverse plane, specifically to avoid shearing said bolts.

This bearing support 14 is illustrated in greater detail in Figures 2, 2A and 3 to 5. It can thus be seen, in Figure 2, an inclination angle a of the radial arms 17 in axial direction with respect to a transverse plane and, in Figure 3, an inclination angle p of the radial arms 17 in the transverse plane with respect to a radial direction. In the illustrated embodiment, the angle of inclination a is less than or equal to 45 °, while the angle of inclination p is less than or equal to 70 °.

Each radial arm 17 is hollow, thus allowing the passage of a conduit 20 of lubricating fluid, as well as a rupture rotor 21 of the turbine rotor 22. Thanks to the axial inclination of the radial arms 17, the overhang between the inner roots of the radial arms 17 and the turbine rotor 22 can be minimized, which specifically makes it possible to place the sensor 21 particularly close to the turbine rotor 22. On the other hand, to the outer roots of the radial arms 17, the axial separation with respect to the fixing flange 18, which is comparatively rigid and remains comparatively cold during the operation of the turbomotor 1, allows the thermal and mechanical stresses to be better distributed between these outer roots and the fixing flange 18. Furthermore, this axial separation also allows the outer roots of the radial arms 17 of the blade heads 23 of the turbine rotor 22. In order to avoid too large rigidity of the annular crankcase segment 16 in the vicinity of these outer roots, the fixing flange 18 is cut in front of them.

Thanks to the tangential inclination of the radial arms 17, which can be seen in Figure 3, the radial loads of the bearing 13 are not only transmitted in tension-compression by the radial arms 17, but partly in flexion, which allows avoiding a punching of the annular crankcase segment 16 to the outer roots of the radial arms 17.

Turning now to Figure 2A, it can be seen how each radial arm 17 has an aerodynamic profile with a principal axis angularly offset with respect to the axial direction. In the illustrated embodiment, the angle and deviation of the profile is equal to or less than 30 °. Thus, for example, the main axis of the profile can be aligned with the direction of flow of the gases downstream of the turbine rotor 22, thereby reducing the resistance of the radial arms 17 to this flow. At the same time, this deviation increases the stiffness of the radial bending arms in a transverse plane of the bearing support 14.

The central bushing 15 includes an outer ring 32 in which the roots of the radial arms 17, an inner ring 33 forming said outer bearing seat 13, and a conical wall 34 joining said outer and inner rings 32, 33 are located of the central hub 15. In order to limit the mass of the central hub 15, these outer and inner rings 32, 33, and especially the conical wall 34, can be relatively thin. In order to ensure, however, the stiffness of the central hub 15, this conical wall 34, however, has radial ribs 35, as illustrated in particular in Figure 5.

In operation, the bearing support 14 may be subjected to temperatures between 400 and 700 ° C, typically higher in the center of the gas vein than in its radially interior and exterior regions. Nonetheless,

with for example a nickel or cobalt-based refractory alloy, it is possible to obtain, with the polished geometry and the typical dimensions of a turbomotor, radial stiffnesses of the order of 20,000 to 80,000 N / m, and more particularly between 60,000 and 70,000 N / m, while ensuring a good service life, for example at least 6,400 hours of operation.

Although the present invention has been described with reference to a specific embodiment, it is clear that different modifications and changes can be made on these examples without departing from the general scope of the invention as defined by the claims. Consequently, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims (14)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 1. Support (14) for at least one bearing (13) of hot turbomotor section, which includes a central hub (15) incorporating an outer bearing seat for receiving said bearing (13), an annular crankcase segment (16 ) around the central hub (15) and a plurality of radial arms (17) joining said central hub (15) to said annular crankcase segment (16) and inclined in axial direction and in a tangential direction characterized by said radial arms ( 17) are integrated with the central bushing (15) and the crankcase ring segment (16) in a single unit piece. 2. Support (14) according to claim 1, further including at least one fixing flange (18) on an axial end of said annular crankcase segment (16), each radial arm (17) being axially inclined, to starting from a root on said annular crankcase segment (16), in the direction of the axial end of the fixing flange (18). 3. Support (14) according to claim 2, wherein said fixing flange (18) is cut in front of the root of each radial arm (17) on said annular crankcase segment (16). 4. Support (14) according to any one of claims 2 or 3, wherein said fixing flange (18) has at least one positive fitting element (31) for the absorption of stresses in a plane perpendicular to a central axis of the bearing. 5. Support (14) according to any one of the preceding claims, wherein the central hub (15) includes an outer ring (32) in which roots of the radial arms (17), an inner ring (33) are located forming said outer seat, and a conical wall (34) connecting said outer and inner rings of the central hub (15). 6. Support (14) according to claim 5, wherein said conical wall (34) has radial ribs (35). 7. Support (14) according to any one of claims 1 to 6, wherein said radial arms (17) have a tangential inclination angle (3 not exceeding 70 °. 8. Support (14) according to any one of claims 1 to 7, wherein said radial arms (17) have an axial inclination angle not exceeding 45 °. 9. Support (14) according to any one of claims 1 to 8, wherein said radial arms (17) each have an aerodynamic profile with an angular deviation from an axial direction. 10. Support (14) according to claim 5, wherein said aerodynamic profiles have a deflection angle and not greater than 30 °. 11. Turbomotor (1) which includes at least one support (14) according to any one of the preceding claims. 12. Turbomotor (l) according to claim 11, wherein said support (14) is located adjacent downstream of a turbine rotor of the turbomotor (1) and said radial arms (17) are axially inclined in the upstream direction from of said annular crankcase segment (16). 13. Turbomotor (1) according to claim 12, wherein said support (14) includes a fixing flange (18) located on an axial end upstream of said annular crankcase segment (16). 14. Turbomotor (1) according to any one of claims 11 to 13, includes at least one compressor (4, 5), a combustion chamber (6), a first combustion gas turbine (7) coupled in rotation to the minus a compressor (4, 5) by a first rotating shaft (8), and a second combustion gas turbine (9) coupled in rotation to a power outlet by a second rotating shaft (10), and in which said unit support (14) supports at least one bearing (13) of said second rotating shaft (10).